Ascorbic acids and methods of making same



Patented July I I UNITED STATES sscoanro-aoms sun neurons or \mxmo sans v W. adrenal. mm,

or to Winthrop h ammo l-Flea Germany, assignssnicai Company, Inc., New

York, N. Y., a corporation of New York No Drawing.

Application May 12, 1938, 808M No. man. In am, May zs. 1m

1 cum (0!. sac-s44) The present invention relates to ascorbic acids. and-to methods of making same. The ascorbic acids have the following typical wherein x may stand for 0 or a low whole num-.

her. In this formula. the special arrangementoi the. H-atoms and OH-groups in relation to the axis or the C-atoms has not been taken into ac- In U. S. Patent No. 2,068,453 a method for preparing ascorbic acids is described which substantially comprises causing a glyoxylic acid cater to act upon an aldo-sugar in an alkaline medium.

Now I have found a further method for preparing ascorbic acids. The new process is based on the observation that the atomic grouping /O c/ 41-OH 45 an... I

characteristic of the said acids is also formed by causing a mesoxalic acid ester to act upon an aldo-sugar in the presence of an alkaline agent, for instance in an aqueous or alcoholic solution. For producing the alkaline reaction sodium hydroxide, alkali metal cyanides, potassium carbonate, sodium alcoholate or organic bases. such as piperidine, are suitable. It is advisable to carry out the reaction with exclusion of air in an inert gas, for instance in a nitrogen atmosphere, and to heat the solution of the reaction components to boiling. Instead of the tree aide-sugars there 80 may likewise be used the derivatives of these compounds which are transformed into aidov sugars by the action of an alkaline agent. Suitable compounds of this kind are.' ior'instance, the acyl derivatives of the aldo-sugars, such as v tetracetyi ar'abinose, pentacetyl glucose and the ii like, furthermore for instance the acetylized aldonic acid nitriles (G. Zemplen 8; Kiss, Berichte I der Deutschen Chemischen Ges'ellschait .60 (1927) 165), such as the tetracetyl-levo-xylonic acid nitrile. 10

The course of the reaction is illustrated by the iollowingreaction scheme:

H levo-x ionic acid nitrile (unstable ntermediate product) levo-threose mssoxalic acid ester OH H 0H OH 0 lave-ascorbic acid 35 The following examples serve to illustrate the invention, but they are not intended to limit it thereto; the parts are by weight unless otherwise I stated: 40

'1. 'Levo-aluco-ascorbic acid 1 mol of levo-arabinose is boiled for 10 minutes in a reflux apparatus together with a solution of 2 mols of mesoxalic acid ester in about 10 parts I of methanol after 3 mols of sodium cyanide have 45 been added. When acidified with alcoholic hydrochloric acid 28 per cent of the theoretic quantity of levo-gluco-ascorbic acid may be determined by titration with an iodine solution. By a known method, for instance by precipitation with 50 lead acetate, the content of ascorbic acid may be enriched and, if desired, the acid may be obtained in pure condition. All operations should, as far as possible, be carried out with exclusion 01' oxygen.

2. Leno-ascorbic acid 7.9 parts of tetracetyl-levo-xylonic acid nitrile (Berichte der Deutschen Chemischen Gesellschatt, (1927) and 8.7 parts of mesoxalic m acid ethyl ester are dissolved, while gently heating, in parts by volume of absolute methanol, the clear solution is cooled to +10 C. and. mixed at room temperature in a nitrogen atmosphere with '75 parts by volume of a N/l sodium methylate solution. The mixture is heated thereby to about 25 C. The solution assumes a feebly yellow coloration and after some minutes a precipitate begins to separate. After a storing of 12 hours at room temperature 50 parts by volume of a 4-H- solution of hydrochloric acid in alcohol are added.

46 per cent of the theoretic quantity of levoascorbic acid may be determined by titration with an iodine solution.

The product is isolated in known manner, for instance by evaporation, extraction with alcohol of the residue which, as far as possible, is freed from hydrochloric acid and sodium chloride, precipitation with lead acetate and decomposition of the lead salt with hydrogen sulfide. After recrystallization the substance thus obtained melts at 185 C. to 189 C. with decomposition. The rotation in water is (00 22 and in methanol i= I claim: 1. The process of preparing ascorbic acids which comprises reacting a mesoxalic acid ester with glucose in the presence of an alkaline agent.

2. The process of preparing ascorbic acids which comprises reacting a mesoxalic acid ester 6. The process of preparing ascorbic acids which comprises reacting in the'presence of an alkaline agent a mesoxalic acid ester with a member of the group consisting of aide-sugars and the derivatives thereof which are transformed into aldo-sugars by the action of an alkaline agent,

7. The process of preparing ascorbic acids which comprises reacting in the presence of an alkali metal cyanide a mesoxalic acid ester with a member of the group consisting of aldo-sugars and the derivatives thereof which are transformed into aldo-sugars by the action of an alkaline agent.

BURCKHARDT I-IEIFERICH. 

